With the recent trend toward large-sized and large-capacity application apparatuses, a power semiconductor device having a high breakdown voltage, a high current capacity, and high-speed switching characteristics has become necessary.
Accordingly, many researches and developments are being conducted on MOSFETs (metal oxide semiconductor field effect transistors) using silicon carbide (SiC), instead of conventional MOSFETs using silicon. Particularly, there is a lot of development of vertical trench MOSFETs.
In the vertical trench MOSFET, a channel is formed in a p type epitaxial layer on both sides of a trench. The width of the channel is proportional to the thickness of the p type epitaxial layer.
The channel width can be lengthened to increase the amount of conduction current; however, the p type epitaxial layer has to be made thicker because the channel width is proportional to the thickness of the p type epitaxial layer, resulting in an increase in the area of the semiconductor device.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the inventive concept and therefore it may contain information that does not form the prior art.